Eight cases of anomalous position of the left brachiocephalic vein were demonstrated by CT. Six coursed downward lateral to and below the aortic arch to enter the superior vena cava (SVC). Two cases were double left brachiocephalic veins. The superior branch was in the normal position, but the inferior vessel coursed below the aortic arch. Most of these subaortic left brachiocephalic veins enter the SVC at the same level or caudal to the azygous arch. Only two cases were associated with congenital heart disease. This anomalously positioned vessel is asymptomatic but must be distinguished from the pulmonary artery and persistent left SVC, especially when open heart surgery for cardiac malformations is being considered.